ABSTRACT: Obesity and its associated co-morbidities is pandemic and with scientific developments, many combating therapies are in prevalence. Bariatric Surgery (BS) is considered most effective treatment for morbid obesity. After the surgery however weight regain can occur in 20-30% cases. It has also been observed that some patients do not achieve successful outcomes of weight loss or even if they do so, they are unable to maintain it. Various factors like food choices, Basal metabolism, energy expenditure, lifestyle modifications and hormonal changes are seen to affect the weight status after surgery. This review study depicts factors as well as the mechanism of weight regain post bariatric surgery. It is imperative that weight gain occurs in patients, therefore, more studies are required towards the prevention and care in these subjects. Keywords: obesity, bariatric surgery, weight regain